Sound reproducer



Dec. 18, 1934. 1:; B CAMPBELL I 1,984,963

SOUND REPRODUCER Filed Jan 25. 1955 Patented Dec. 18, 1934 UNITED STATES SOUND REPRODUCER Robert B. Campbell, Vancouver, British Columbia, Canada Application January 25,

7 Claims.

This invention relates to improvements in the construction and design of sound reproducing apparatus wherein simplicity and sturdiness are exemplified to reproduce sound in correct tonal qualities throughout the whole of the harmonic scale.

It is a well known fact to those versed in the science of radio sound reproduction that lost intensity and distortion of the high and low notes at both ends of the harmonic scale are common in sound reproducers as constructed today and it is to correct this fault that my improvements are directed as one of its objects.

Another failing of present day sound reproducers is their inability to reproduce at full volume orchestration without distortion and more especially is this so if the music to be reproduced consists of a mixed orchestra.

It is one of the objects of my improvements to produce full volume orchestration without the slightest distortion.

Another fault common to the ordinary run of sound reproducing apparatus is delicacy of parts and failure to preserve true fidelity and clarity of the intermediate range of the harmonic scale while emphasizing or attenuating the bass or treble notes, and it is one of the objects of my improvements to provide a sound reproducer that will reproduce with exactitude and fidelity the 1 original clarity and tone of all the notes comprising the music or piece being played, without resorting to delicacy of parts.

Another particular object of my invention is to suppress and dampen all spectre-like notes, meaning by this those notes that are originated by echolike vibrations produced within the confines of the cabinet or covering of the apparatus by reverberation of the original note striking some portion of the cabinet whereby an echo-like reproduction on a different scale or vibration rate to that of the original note is produced.

To the attainment of these and other objects I have invented the sound reproducing apparatus that is the subject matter of this application and which is further illustrated in the accompanying drawing and fully described in the following specification forming part of this application and in which:

Figure 1 is a front view of the sound diaphragm and amplifier and shows the central diaphragm and concentric annulus rigidly secured together.

Figure 2 is a cross sectional view taken on the line 2-2 of Figure l and this shows the sound diaphragm in section and. the other parts such as the cone member, polarizing magnet and stays 1933, Serial No. 653,533-

in plan. In this view the cone member is shown rigidly attached to the axis of the central diaphragm, also the cross sectional shape of the central diaphragm and concentric annulus is shown.

Fig. 3 is an enlarged detail section showing the prongs 31: on the strips 3 embedded in the dia phragm and annulus.

In this. drawing like numerals indicate like parts and the numeral 1 indicates a central diaphragm member having gradually tapering surfaces from its axis to its peripheral edges.

This diaphragm may be formed of a variety of materials such as paper or papier-mach or other compositions or it may be of metal or porcelain or other hard substances.

Surrounding the central diaphragm member 1 and rigidly attached thereto is a concentric annulus 2 the diameter of which is approximately three times that of the central diaphragm 1.

The central cross sectional thickness of the walls or web of the concentric annulus 2 is approximately eight times that of the axis of the central diaphragm member 1 and I prefer to construct both these members of similar material, although it is not requisite that they be so as they may be constructed of diiierent, materials.

The members illustrated in the drawing are constructed of papier-mach and are joined together by a metal binding strip 3 having prongs 3r imbedded in the material to make a rigid and secure fastening.

The concentric annulus 2 which I term a diffusion ring has its cross sectional area thickest intermediate its outer and inner peripheral edges.

Secured rigidly to the axis of the central diaphragm l is the cone member 4, the outer end 15 of which is formed parallel with the axis of the cone and upon which is wound the voice coils 6, the terminals of which are connected to the usual output terminals (not shown) of the source of electrical impulses. The coils 6 are positioned within the magnetic field of the polarizing magnet '7.

The concentric annulus 2 is rigidly secured by the brace rods 8 to any convenient part of the structure comprising the sound reproducer and in the drawing the rods 8 are shown secured to the field pole supports of the magnet 7.

It is requisite that the central diaphragm 1 and the concentric annulus 2 be rigidly secured together and while in the drawing there is shown the metal binding strip 3 for this purpose, it is to be understood that other securing means and medium may be used for this purpose.

It is also an absolute necessity that the cone member 4 be rigidly secured at its vertex to the axis of the diaphragm and any convenient means may be adopted to this end.

While throughout this specification I have referred to the central diaphragm 1 and the concentric annulus 2 as being separate members, it is to be understood that they could be constructed as an integral member by the use of suitable dies and equipment and I therefore do not confine my invention to multiple members.

In operation the device functions as follows: Electrical impulses are set up in the voice coils 6 from the usual electrical equipment and these impulses are impressed orv impinged upon the cone 4 by which they reach the central diaphragm 1 to set up vibrations thereupon connected concentric annulus 2.

The vibrations thus set up are amplified to a degree of audibility by being impressed and released upon the surrounding air medium through the inertia of the vibrations leaving the surfaces of the sound diaphragm.

Having now fully described my invention what I claim and desire to be protected. in by Letters Patent, is:

1. In a sound reproducing apparatus of the kind described, a support, a central diaphragm member having walls of tapering thickness from the axis thereof to its peripheral edge, a concentric annulus surrounding said central diaphragm member and rigidly secured thereto, said annulus having a web thickness approximately eight times that of the axis of said central diaphragm, and means for rigidly connecting said diaphragm and annulus to said support, said means comprising brace rods having one end'connected to said annulus and the, opposite ends converging to and connected to said support.

2. In a sound reproducing apparatus, a support, a central diaphragm, an annulus concentric with said diaphragm, means rigidly connecting said diaphragm and said annulus together at the outer edge of the diaphragm and inner edge of the annulus, brace elements rigidly connected to the central portion of the body of said annulus and extending toward and rigidly connected with said support.

3. In a sound reproducing apparatus, a support, a central diaphragm, an annulus concentrio with said diaphragm, means rigidly connecting said diaphragm and said annulus together at the outer edge of the diaphragm and inner edge of the annulus, brace elements rigidly connected to the central portion of the body of said annulus and converging toward and rigidly connected with said support, said diaphragm and said annulus each having convex faces with their greatest and its thicknesses at the central portions of the bodies of the diaphragm and annulus, respectively.

4. In a sound reproducing apparatus, a support, a central diaphragm, an annulus concentric with said diaphragm, means rigidly connecting said diaphragm and said annulus together at the outer edge of the diaphragm and inner edge of the annulus, brace elements rigidly connected to the center portion of the body of said annulus and extending toward and rigidly connected with said support, said diaphragm and said annulus each having convex faces with their greatest thicknesses at the central portions of the bodies of the diaphragm and annulus, respectively, said annulus being of a diameter approximately three times that of said diaphragm.

5. In a sound reproducing apparatus, a support, a central diaphragm, an annulus concentric with said diaphragm, means rigidly connecting said diaphragm and said annulus together at the outer edge of the diaphragm and inner edge of the annulus, brace elements rigidly connected to the central portion of the body of said annulus and extending toward and rigidly connected with said support, said diaphragm and said annulus each having convex faces with their greatest thicknesses at the central portions of the bodies of the diaphragm and annulus, respectively, said annulus being of a thickness approximately eight times that of said diaphragm.

6. In a sound reproducing apparatus, a support, a central diaphragm, an annulus concentric with said diaphragm, means rigidly connecting said diaphragm and said annulus together at the outer edge of the diaphragm and inner edge of the annulus, brace elements rigidly connected to the central portion of the body of said annulus and extending toward and rigidly connected with said support, said diaphragm and said annulus each having convex faces with their greatest thicknesses at the central portions of the bodies of the diaphragm and annulus, respectively, said annulus being of a diameter approximately three times that of said diaphragm, and said annulus being of a thickness approximately eight times that of said diaphragm.

7. In a sound reproducing apparatus, a central diaphragm, an annulus concentric with said diaphragm, means rigidly connecting said diaphragm and said annulus together at the outer edge of the diaphragm and the inner edge of the annulus, brace rods secured to the central portion of the body of said annulus, a support, said support being centrally located with respect to the axis of said diaphragm and being of lesser diameter than that of the central portion of said annulus and said rods converging to and secured to said support.

ROBERT E. CAMPBELL. 

